Chapter 4, Hemodynamic disorders, Thromboembolism, and shock Flashcards
defined hemostasis?
blood clotting
thrombosis definition?
inappropriate clotting
Embolism definition?
migration of clots which could cause ischemic cell death (infraction)
Hyperemia definition?
active process resulting from arteriolar dilation and increased blood inflow (inflammation or exercising muscle)
tissue appears redder due to oxygenated blood.
Congestion definition?
passive process resulting from impaired outflow of venous blood from tissues. (cardiac failure or local obstruction)
tissue appears blue due to deoxy-blood (cyanosis).
name that is used to describe fluid accumulation in pleural cavity, pericardial cavity, or the peritoneal cavity
- pleural cavity (hydrothorax)
- pericardial cavity (hydropericardium)
- peritoneal cavity (hydroperitoneum or ascites)
definition of Anasarca?
a severed, generalized edema marked by profound swelling of subcutaneous tissues and accumulation of fluid in body cavities.
the does the vicious cycle of fluid retention occur during edema?
increased venous hydrostatic pressure in patients with congestive heart failure. The reduced cardiac output results in hypoperfusion of the kidneys, triggering the renin-angiotensin-aldosterone axis, increasing blood volume that the failing heart may not be able to compensate for. thus edema worsens.
causes of Edema?
- increased hydrostatic pressure (heart failure)
- reduced plasma osmotic pressure (low albumin)
- lymphatic obstruction
- Sodium and water retention
what are the causes of reduced plasma osmotic pressure?
reduced Albumin concentration which makes up upto half of the proteins in the blood.
- Nephrotic syndrome: leaky glomerular capillaries causes albumin and protein loss.
- Reduced albumin synthesis (liver disease)
define pitting edema
when a finger is used to apply pressure to an edema causing a finger-shaped depression.
define hemorrhagic diatheses
clinical disorders increasing the risk of hemorrhage.
extensive hemorrhage can result in jaundice from the massive RBC breakdown.
define hemarthrosis
accumulation of blood in the joints.
Petechiae definition?
1-2mm diameter hemorrhages into the skin, mucous membranes or serosal surfaces (low platelet count, defective platelet function, loss of vascular wall support due to low vitamin C.
purpura definition?
a larger 3-5mm hemorrgaes (caused by trauma, vascular inflammation, and also the same disorders as petechiae.
ecchymoses definition?
subcutaneous hematomas (a bruise)
why does internal bleeding not lead to iron deficiency?
internal blood loss, the RBC are phagocytosed and the iron is efficiently recycled.
Glanzmann thrombasthenia
bleeding disorder caused by GP IIBb/IIIa in platelets.
what does Coumadin do?
antagonizes the enzymatic reaction that produce y-carboxylated glutamic acid using vitamin K as cofactor, it is a widely used anti-coagulant.
prothrombin time tests what?
assesses the function of the proteins in the EXTRINSIC pathway.
Partial thromboplastin time (PTT) test what?
Intrinsic pathway proteins function.
function of Thrombin?
- conversion of fibrinogen into crosslinked fibrin
- platelet activation (via PAR protease activated receptor)
- proinflammatory effects
- anti-coagulant effects
3 methods to prevent the coagulation plug from spreading from the site of injury?
1: the blood washes out the pro-coagulant factors
2: the negative charges on platelet surface is limited to site injury
3: the anticoagulant factors expressed adjacent to site of injury. (plasminogen made into plasmin via XII and tPA) a2-plasmin inhibitor, inhibits free plasmin.
3 methods to prevent the coagulation plug from spreading from the site of injury?
1: the blood washes out the pro-coagulant factors
2: the negative charges on platelet surface is limited to site injury
3:
process of the anti-coagulant effect of endothelium?
Thrombin binding to thrombomodulin and protein C which then cleaves factors Va and VIIIa.
what is the Virchow’s triad?
in thrombosis the primary abnormalities that lead to intravascular thrombosis:
- Endothelial injury
- Abnormal blood flow
- Hypercoagulability
how does inflammation cause coagulation?
endothelial cells actiavted by cytokines downregulate the expression of thrombomodulin.
inflammed endothelium can also down regulate protein C
-activated endothelium secrete plasminogen activator inhibitor (PAI), which limit firbinolysis, (inflammation can be disturbed)
how does abnormal blood flow cause thrombosis?
- stasis and turbulence promote endothelial ell activation and enhanced pro-coagulant activity through flow-induced changes in endothelial gene expression.
- Stasis allows platelets and leukocytes to come into contact with the endothelium when the flow is sluggish.
- Stasis also slows the washout of activated clotting factors and impedes the inflow of clotting factor inhibitors.
what would cause hypercoagulability?
- Leiden mutation
- prothrombin gene mutation
what is Heparin-induced thrombocytopenia syndrome?
this syndrome occurs in up to 5% of patients treated with unfractionated heparin. marked by the development of autoantibodies that bind complexes of heparin and platelet membrane protein. the result is a prothrombic state.
define anti-phospholipid antibody syndrome?
autoimmune, hypercoagulable state caused by antiphospholipid antibodies. It provokes blood clost in both arteries and veins and can result in pregnancy related complications.
The 2 antibody blood tests confirm the presence of either lupus anticoagulant.
4 fates of the thrombus?
1: propagation (clot grows)
2: embolization (pieces of the clot dislodge)
3: Dissolution (clots dissolve)
4: Organization and recanalization (vessels may form through the clot re-establishing the original lumen.)
what can an embolus be made of?
thrombus, fat droplets, bubbles of air or nitrogen, atherosclerotic debris, tumor fragments, bits of bone marrow, or amniotic fluid.
arterial versus venous fromed thrombus?
venous usually ends up in the lungs and originates in the legs
arterial usually ends up in extremities and possibly the CNS
Fat embolism definition?
during skeletal injury (fracture) small fat droplets are released into the circulation.
clinical symptoms appear 1-3 days after injury.
platelets can bind to the fat droplet
thrombocytopenia
low platelet count
what injury is caused by fat globules?
they can occlude vessels by triggering platelet aggregation.
the fatty acids damage the endothelium.
Amniotic fluid embolism?
amniotic fluid enters the mother blood and triggers reactions. the coagulation pathway and the innate immune system.
Red vs white infarcts
Red infrarcts are hemorrhagic infarcts and usually occur in less dense tissue like the lungs and GI tract. White infarcts (also called anemic infarcts) are non-hemorrhagic and are more likely in denser tissues like the myocardium (heart muscle) and other muscle tissues as well as the kidneys and spleen.
Shock definition?
- cardiogenic chock
- hypovolemic shock
- septic shock (inflammation)
Septic shock causes?
gram-positive bacteria followed by gram-negative bacteria and fungi.
pathogenesis of septic shock?
- inflammatory and counterinflammtory responses
- endothelial activation and injury
- induction of a procoagulant state (low blood flow causes stasis)
- metabolic abnormaliteis (inflammatory mediators suppress insulin release and cause insulin resistance)
- organ dysfunction
